Easy opening can end



Sept. 26, 1967 E. c. FRAZE 3,343,713

EA'SY OPENiNG CAN END i Filed Jan; 29, 1965 u 3 5 45 4o F ll I F 10 a F' 49 WW0 fi Er/na/ G in?! United States Patent 3,343,713 EASY OPENING CAN END Ermal C. Fraze, 355 W. Stmop Road,

Dayton, Ohio 45429 Filed Jan. 29, 1965, Ser. No. 429,063 8 Claims. (Cl. 22054) This invention relates to a metal container having a portion of its wall weakened by scoring to form a tear strip that may be easily manually severed for access to the contents of the container, More particularly, the invention is directed to the problem of incorporating a panel or insert of relatively expensive, soft, non-ferrous metal in a container wall made of less expensive, tough, ferrous metal with a tear strip formed in the panel or insert.

The desirability of incorporating a panel of relatively soft metal, for example, aluminum alloy, in a container wall of tough metal, for example, tin coated steel, arises from the fact that it is difiicult to form a readily separable tear strip in the tin coated steel and too often the removal of the tear strip leaves a hazardous jagged edge. Undue manual force is required to remove a steel tear strip and if the tab is attached to the tear strip to serve as a handle for removing the tear strip, the excessive stressing of the metal structure required for severance of the metal is too apt to cause separation of the tab from the tear strip instead of separation of the tear strip from the container. Incorporation of a softer metal insert or panel into the steel container wall avoids these difficulties and combines the economy of making the container wall largely of steel with the advantage of forming the tear strip in relatively soft metal, but the composite structure of the wall does present the problem of installing the panel or insert efficiently and economically in a fluid-tight manner.

One heretofore suggested solution to this problem is to cut a substantially rectangular opening in the steel wall of the container and to place a flanged insert of softer sheet metal into the rectangular opening with the flange of the insert folded to grip the rim of the rectangular opening, a suitable sealant being employed to make the joint fluid tight. The panel insert is formed with a peripheral flange and nests into the rectangular opening in the manner of a plug with the insert folded into engagment with the rim of the rectangular opening around three sides of the insert. The insert is scored to form a tear strip which is continued as a free tongue that extends from the fourth side of the insert to serve as a tab or handle for removing the tear strip.

One disadvantage of this suggested solution is that the insert on the fourth side that forms the free tongue is not folded into positive gripping engagement with the rim of the rectangular opening because folding the tear strip on itself to form the joint would make it too difficult, if not impossible, to pull the tear strip away from the insert. Consequently, the fourth side of the insert merely overlaps the rim of the rectangular opening instead of positively engaging the rim and only the interposed sealant is relied upon to make the joint fluid tight. In practice, it is only too easy for leakage to develop along this vulnerable part of the joint between the insert and the steel wall of the container and especially so because two slits are cut in the insert adjacent this part of the joint. Also, if the sealant is durable and thick enough to adequately seal the open section on the fourth side, the sealant because of its adhesive properties, renders difiicuit the removal of the tear strip from the panel insert.

A further disadvantage is that removal of the tear strip exposes a strip of sealant adjacent the opening and the exposed sealant is not only unsightly, but also suggests the possibility of contamination when the contents of the container issue from the opening. The exposed sealant is especially objectionable when the consumer drinks liquid directly from the container.

A further disadvantage of the suggested solution to the problem is that the surface of the aluminum insert is offset inwardly from the surface of the metal wall to form a recess or shallow well around the tear strip. The shallow well tends to trap dust and foreign material immediately adjacent the opening that is formed by the removal of the tear strip.

The present invention meets the above problem, in part, by forming an opening in the steel wall of the container that is of generally circular configuration instead of rectangular; in part, by positively mechanically attaching the soft metal insert to the steel wall by means of a tightly rolled seam that is continuous around the rim of the opening; in part by locating the seam inside the container so that the outer surface of the insert may be flush with the outer surface of the surrounding container wall, i.e., the exposed face of the insert is disposed in the same plane as the steel wall; in part, by spacing the whole tear strip in the insert radially inward from the surrounding continuous seam to avoid any conflict between the structural requirements of a tear strip and the structural requirements of a fluid tight seam; and, in part, by attaching a separate tab to the tear strip instead of forming one side of the insert with an integral tongue to serve as a tab.

To carry out this concept, the container wall is formed with an opening having a rim that curves without abrupt changes in direction, the opening being preferably of generally circular configuration, and the opening is formed with an inwardly turned flange. Usually, the container wall is a can top or end wall and, fortuitously, the flanged circular opening may be formed at no extra'cost when the can end is stamped out of sheet steel stock. The soft metal insert is formed with a continuous marginal flange and initially the insert is nested into the opening of the container wall with the flange of the insert turned inwardly in face-to-face contact with the inward flange of the container opening. Since the two flanges are to be rolled together to form the continuous seam with the insert flange rolled over the container flange, the insert flange is preferably of greater axial dimension than the container flange and preferably the rims of both flanges are slightly flared or curved outward in advance of the seaming or curling operation.

A single die operation curls the two flanges into a continuous seam of substantially solid metal that makes it unnecessary to add sealant, although a plastisol sealant may be incorporated in the seam if desired. The

plastisol sealant is particularly desirable to prevent anodic action where the can is intended to hold a substance which would serve to produce an anodic action at the seam formed. The fact that the rim of the opening in the steel wall is curved without abrupt change in direction makes it possible to fabricate a seam that is uniform in cross section around the periphery of the insert. In the preferred practice of the invention, the rolled continuous seam protrudes into the interior of the container with the outer surface of the insert flush with the outer surface of the container wall. Preferably, but not necessarily, the rolled seam is subjected to a final compression operation toresult in a relatively thin, flat seam with the layers of sheet material folded compactly for further assurance against leakage.

Other and additional advantages and features of the present invention will become apparent to those skilled in the art from a study of the accompanying specification and drawings which form a part thereof, and wherein:

FIGURE 1 is a plan view of a can end constructed in accordance with the teachings of this invention;

FIGURE 2 is a plan view of the underside of the can end illustrated in FIGURE 1;

FIGURE 3 is an enlarged cross-sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is an enlarged plan View of the top of the insert used in forming the can end illustrated in FIGURES 1-3, inclusive.

FIGURE 5 is a cross-sectional view of the insert of FIGURE 4 taken along line 5-5 of FIGURE 4 and looking in the direction of the arrows;

FIGURE 6 is an enlarged fragmentary cross-sectional view of that portion of the tin-coated steel material of the can end illustrated in FIGURES 1-3 inclusive, showing the opening into which the insert of FIGURES 4 and 5 is inserted;

FIGURE 7 illustrates schematically the positioning of the insert into the opening illustrated in FIGURE 6 and the dies for curling the flanges for permanently attaching the insert thereto;

FIGURE 8 shows the dies of FIGURE 7 in their closed position having curled flanges of the can end and insert to form a unitary construction;

FIGURE 9 illustrates schematically the dies for flattening the seamed jointure between the insert and body of the can end for an insured seal; and

FIGURE 10 is a fragmentary view, showing in section the flanges of the can end and insert as coated with the desired sealant prior to the curling or seam-forming operation.

FIGURES 1, 2 and 3 show the completed can end 10 of the present invention having a curled peripheral edge 12 for connecting the end to the can body (not shown) and an insert or panel 14 mounted in an opening in the can end, the insert 14 being provided with a tear strip 1-6, formed by score lines 18, to one end of which a tab 2t) is permanently attached. Although the tab 20 can be permanently attached to the one end of the tear strip 16 by any suitable means, in the illustrated embodiment of the invention, the tab 20 is attached to the tear strip 16 by a hollow rivet 22 formed integral with the wall of the insert 14. The tab 20 forms a lever to be manually grasped by a user to bring about severance of the tear strip 16 from the insert 14. The tab 20, as illustrated more clearly in FIGURE 3, lies substantially flat and in close proximity with the top surface 24 of the can end to permit stacking of the can bodies in a conventional manner.

The body 26 of the can end 10 is formed from tinplated steel strip stock, commonly known in th'eindustry as tin plate, while the insert 14 is formed of a suitable, relatively soft aluminum alloy. Since the tear strip 16 and the rivet 22 for attaching the tab 20 thereto are both formed out of the aluminum alloy of the insert 14, the opening of the sealed can is accomplished entirely within the area of the insert without the necessity of disturbing the surrounding tin plated steel. Thus the present invention provides a means of manually opening a can end formed largely of tin plated steel by severing a tear strip formed solely of the aluminum alloy of the insert. This feature of the invention is advantageous in that the can end is easier to open and moderate manual force will not pull the tab away from the tear strip. At the same time, the can end formed in accordance with the teachings of this invention has the cost advantages of tin plated steel for a major portion of the can end.

Turning now to FIGURES 4 and 5, there is shown the aluminum insert 14 formed by any suitable method, such as by a stamping and forming operation. The insert as formed is provided with a downwardly extending integral peripheral flange 34 for purposes of attaching the insert permanently within the opening of the can end.

The main body portion 26 of the can end 10 is formed by any suitable method such as by stamping out of tinned steel sheet stock and is apertured as at 36 and provided with a downwardly extending peripheral hub or flange 38. This hub or flange 38 is preferably provided with a flare 40 to cooperate with die means which, as will be later made clear, joins the insert to the can end.

The joining of the insert into the flanged opening of the body portion 26 of the can end can be brought about by any means desired, and FIGURES 7 and 8 illustrate schematically die means which may be used for permanently attaching the insert 14 to the body portion 26. As illustrated in these figures, the die means comprises an upper die or anvil 42 which is provided with a flat surface 44 which engages the top surface 24 of the can end and the top surface 30 of the insert after the latter has been placed in position in the aperture. A lower die 48 is formed with an annular groove or recess 59 which, as the dies are moved together, causes the flanges 34- and 38 to be rolled together to form a curled seam to permanently mount the insert in the opening 36 of the can end 10. The groove 51 has a diameter such that it contacts the lower end of the flange 34 of the insert, and as the dies 42 and 48 move toward one another, the surface of the groove forces the flanges 34 and 38 to curl within one another to form a seam, as illustrated at 56 in FIGURE 8.

It is to be noted that flange 34 is slightly longer, i.e., extends downwardly further than flange 38 and the very end of the flange 34 is provided with a slight outwardly extending flare 58 similar to the flare 40 of the flange 38 to assist in the curling operation. The flare 58 may be formed on the flange 34 either before the insert is placed into the opening of the body portion or afterwards, as desired. Where the flare 58 is placed on the flange 34 before insertion of the insert 14 into the opening 36, then the insert must be inserted in the opening from the flanged side of the body portion, either before or after the body portion is placed in position on the anvil 42.

At this point, the installation of the insert 14 in the body portion 26 of the can end 10 may be regarded as finished since the curled or rolled seam 56 is of high mechanical strength and is liquid-tight even in the absence of sealant in the seam, although a plastisol sealant may be used. When a sealant is used, it is now preferred to coat the flanges 34 and 38 prior to the step of curling the flanges to form the seam 56. This coating step may be completed by merely dipping the flanges into a bath of the sealant to form a film of the sealant on the flanges at least on the surface areas thereof shown by FIGURE 10.

Moreover, if desired, the seam 56 may be flattened by an additional operation. For this purpose, the can end is then placed in another set of dies which includes an anvillike die 60 and an upper die 62, and where the curled seam 56 is squeezed and flattened as shown at 64 as one die is moved toward the other.

After the can end 10 with the insert 14 is permanently joined thereto, lines of weakness in the form of score iines are formed in the insert 14 to provide the severable tear strip 16. The lines of weakness may be formed in any suitable configuration to form the severable tear strip such as, for example, the tear strip illustrated in FIGURE 1 which when removed from the insert, provides a pouring spout through which the contents of the can may be discharged.

To permit the manual removal of the tear strip 16 to form the opening, the lever or tab 20 is permanently connected to the one end of the tear strip and although the tab 20 may be permanently joined to the tear strip by any joining method desired, in the illustrated embodiment of the invention the tab is joined to the tear strip by the rivet 22 formed integral with the planar wall of the insert 14. The integral rivet may be formed and the jointure completed by the method of my copending application, Ser. No. 280,545, but however formed, the rivet 22 extends through a flanged opening in the tab after which the projecting end of the rivet is upset or staked to form an annular bead 70 clampingly mounting the tab 20 to the tear strip 16.

The tab 20 may be of any suitable construction, but in the illustrated embodiment of the invention comprises a segment of sheet metal having the edges thereof folded for strengthening purposes and divided into a minor end portion 72 that is connected to the hollow rivet 22 and a major portion 74 that constitutes a second class lever. Thus, the lever 74 is connected to the hollow rivet 22 by a web of sheet metal that is freely bendable along a dotted line 76 to permit the lever to swing relative to the rivet. The metal of the tab is formed with divergent slits 78 at the opposite ends of the dotted line 76 to provide the second class lever 74 with a pair of fulcrum ends 80 that extend beyond the dotted line and straddle the rivet 22 outside of the area of the tear strip 16. Thus, the lever has a forked fulcrum end and it is apparent that lifting the free end of the lever 74 swings the forked fulcrum end against the can end to apply a highly effective lifting force to the rivet 22 to initiate severance of the tear strip.

While the method has been described as first forming a tin end such as illustrated in FIGURES 1, 2 and 3, it can be appreciated that the method of installing the insert could be performed prior to the time the tin end configurations have been severed from their original tinned steel sheet stock. Similarly, the Work operations of scoring and attaching the tab to the insert may be performed on the insert prior to its being placed in the curling and folding dies 42, 48 and 60, 62, the dies in this case being shaped to accommodate the tab and its means for joining the same to the insert so that the top surface will lie coplanar with surface 26 of the can end.

It is to be stressed that while the invention is illustrated by showing a tab suitable to be attached to the tear strip 16 by a rivet integral with the insert 14, obviously the tab may be of any suitable type and attached to the tear strip in any conventional manner as by spot or pressure welding operations.

The present invention, as should now be understood, supplies a can end, the major or body portion 26 of which is formed of tin-plated steel but yet includes the insert 14 with its score lines providing a tear strip which can be as easily removed as a tear strip of an all aluminum can end. Furthermore, the seamed attachment of the aluminum insert to the tin-plated steel body portion acts as an expansion joint which tends to resist internal pressures which ordinarily will cause a one-piece can end to bulge outwardly. As the seamed connection does serve as an expansion joint, upon reduction of the pressure within the can, the can end will tend to return to its original unstressed position so that the searned connection also serve a hi hly useful purpose where the can and its contents are subject to heat before the can is supplied to the market.

It should also be pointed out that even though the tinplated steel stock is apertured the exposed steel is not subject to direct engagement with the contents of the can with which the can end is used as the exposed steel edge is disposed internally of the seam after the seaming or curling operation has been completed. Thus there is no likelihood of the contents of the can reacting with the exposed steel of the body portion 26.

While only a single embodiment of the present invention is disclosed and described herein, it will be readily apparent to persons skilled in the art that numerous changes and modifications may be made Without departing from the scope of the invention. Accordingly, the foregoing disclosure and description thereof are for illustrative purposes only and do not in any way limit the invention which is defined by the claims which follow.

I claim:

1. In a container:

a container wall segment constructed of strong sheet material and having an opening therein;

a panel of relatively soft material covering said openportions of said conainer wall segment and said panel being curled radially one within the other to form a continuous seam in the interior of the container extending continuously and completely around said panel to securely interlock and seal said panel to said container wall segment;

a line of weakness in said panel defining a tear strip;

and

tab means secured to said tear strip on the exterior of the container to initiate severance thereof from said panel.

2. A combination as defined in claim 1 including a hollow rivet integral with said tear strip for securing said tab means to said tear strip.

3. A combination as defined in claim 1 wherein said opening is arcuate.

4. An improvement as set forth in claim 1 in which the tear strip is formed with a hollow rivet;

in which the tab means is attached to the hollow rivet;

and

in which the tab means forms a second class lever hingedly connected to the rivet with a forked fulcrum end of the lever straddling the rivet.

5. In the construction of a tough sheet metal container wherein a panel of softer sheet material is inserted in an opening of the wall of the container and the panel is formed with a manually removable tear strip, the improvement comprising:

the opening in the wall of the container having a curved rim without abrupt changes in direction of the rim;

the material of the panel being positively interlocked with the material of the container wall in a continuous seam of uniform cross section around the periphery of the panel;

the tear strip being spaced radially inward from the continuous seam; and

a separate tab to serve as a handle being attached to one end of the tear strip and overhanging the continuous seam.

6. An improvement as set forth in claim 5 in which the opening in the wall of the container is of generally circular configuration.

7. An improvement as set forth in claim 6 in which the panel is substantially flush with the container wall with the continuous seam protruding into the interior of the container.

8. In combination:

a container wall segment constructed of strong sheet material and having an opening therein, said opening having a rim;

a panel of relatively soft material covering said opening, adjacent layers of said container wall segment and said panel being rolled together radially outwardly of the rim of said opening to form a continuous seam extending continuously and completely around said panel to securely interlock and seal sai'd panel to said container wall segment;

a line of weakness in said panel defining a tear strip;

and

tab means secured to said tear strip to initiate severance thereof from said panel.

References Cited UNITED STATES PATENTS 3,084,826 4/ 1963 Ericson. 3,163,317 12/1964 Biedenstein et al 22054 3,215,306 11/1965 Simpson et al 22054 3,221,924 12/ 1965 Harvey et al 22054 3,223,277 12/1965 Zundel 22053 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner. 

1. IN A CONTAINER: A CONTAINER WALL SEGMENT CONSTRUCTED OF STRONG SHEET MATERIAL AND HAVING AN OPENING THEREIN; A PANEL OF RELATIVELY SOFT MATERIAL COVERING SAID OPENING; PORTIONS OF SAID CONTAINER WALL SEGMENT AND SAID PANEL BEING CURLED RADIALLY ONE WITHIN THE OTHER TO FORM A CONTINUOUS SEAM IN THE INTERIOR OF THE CONTAINER EXTENDING CONTINUOUSLY AND COMPLETELY AROUND SAID PANEL TO SECURELY INTERLOCK AND SEAL SAID PANEL TO SAID CONTAINER WALL SEGMENT; A LINE OF WEAKNESS IN SAID PANEL DEFINING A TEAR STRIP; AND TAP MEANS SECURED TO SAID TEAR STRIP ON THE EXTERIOR OF THE CONTAINER TO INITIATE SEVERANCE THEREOF FROM SAID PANEL. 